U.S. patent application number 17/149264 was filed with the patent office on 2022-07-14 for resolver excitation using threshold band of voltages.
The applicant listed for this patent is Infineon Technologies AG. Invention is credited to Christian Heiling, Thomas Uller.
Application Number | 20220221308 17/149264 |
Document ID | / |
Family ID | 1000005373365 |
Filed Date | 2022-07-14 |
United States Patent
Application |
20220221308 |
Kind Code |
A1 |
Heiling; Christian ; et
al. |
July 14, 2022 |
RESOLVER EXCITATION USING THRESHOLD BAND OF VOLTAGES
Abstract
A device for excitation of a resolver comprising an excitation
coil and one or more sensing coils includes circuitry. The
circuitry is configured to amplify a carrier signal using a first
gain value to generate an excitation signal for output to the
excitation coil of the resolver and determine whether the
excitation signal is outside of a threshold band of voltages. The
circuitry is further configured to amplify the carrier signal using
a second gain value, wherein the second gain value is generated
based on whether the excitation signal is outside of the threshold
band of voltages.
Inventors: |
Heiling; Christian; (Graz,
AT) ; Uller; Thomas; (Gnas, AT) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Infineon Technologies AG |
Neubiberg |
|
DE |
|
|
Family ID: |
1000005373365 |
Appl. No.: |
17/149264 |
Filed: |
January 14, 2021 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G01D 5/2073
20130101 |
International
Class: |
G01D 5/20 20060101
G01D005/20 |
Claims
1. A device for excitation of a resolver comprising an excitation
coil and one or more sensing coils, the device comprising circuitry
configured to: amplify a carrier signal using a first gain value to
generate an excitation signal for output to the excitation coil of
the resolver; determine whether the excitation signal is outside of
a threshold band of voltages; and amplify the carrier signal using
a second gain value, wherein the second gain value is generated
based on whether the excitation signal is outside of the threshold
band of voltages.
2. The device of claim 1, wherein, to determine whether the
excitation signal is outside of the threshold band of voltages, the
circuitry is configured to: determine whether a voltage of the
excitation signal exceeds a combination of a first supply voltage
and a first guard-band voltage; and determine whether the voltage
of the excitation signal is less than a second supply voltage minus
a second guard-band voltage.
3. The device of claim 1, wherein, to determine whether the
excitation signal is outside of the threshold band of voltages, the
circuitry is configured to: output the excitation signal to a first
input of a first comparator of the circuitry; output a first supply
voltage to a second input of the first comparator; apply, with a
first guard-band element of the circuitry, a first guard-band
voltage that offsets a voltage at the first input of the first
comparator or a voltage at the second input of the first
comparator; output the excitation signal to a first input of a
second comparator of the circuitry; output a second supply voltage
to a second input of the second comparator; and apply, with a
second guard-band element of the circuitry, a second guard-band
voltage to offset a voltage at the first input of the second
comparator or a voltage at the second input of the second
comparator.
4. The device of claim 1, wherein the circuitry is further
configured to: output, to controller circuitry, a high rail
detection signal indicating that the excitation signal is in an
upper distortion zone in response to determining that the
excitation signal exceeds the threshold band of voltages; and
output, to the controller circuitry, a low rail detection signal
indicating that the excitation signal is in a lower distortion zone
in response to determining that the excitation signal is less than
the threshold band of voltages.
5. The device of claim 4, wherein the circuitry is further
configured to receive, from the controller circuitry, an indication
of the second gain value, wherein the controller circuitry
generates the second gain value based on the high rail detection
signal, the low rail detection signal, or both the high rail
detection signal and the low rail detection signal.
6. The device of claim 1, wherein the circuitry is further
configured to determine the second gain value based on whether the
excitation signal is outside of a threshold band of voltages.
7. The device of claim 6, wherein, to determine the second gain
value, the circuitry is configured to generate the second gain
value to be less than the first gain value when a voltage of the
excitation signal exceeds a combination of a first supply voltage
and a first threshold or when the voltage of the excitation signal
is less than a second supply voltage minus a second threshold.
8. The device of claim 6, wherein, to determine the second gain
value, the circuitry is configured to generate, during a start-up
operation of the circuitry, the second gain value to be greater
than the first gain value when a voltage of the excitation signal
does not exceed a combination of a first supply voltage and a first
threshold and when the voltage of the excitation signal is less
than a second supply voltage minus a second threshold.
9. The device of claim 6, wherein, to determine the second gain
value, the circuitry is configured to generate, during a
steady-state operation of the circuitry, the second gain value to
be greater than the first gain value when a voltage of the
excitation signal does not exceed a combination of a first supply
voltage and a first threshold, when the voltage of the excitation
signal is less than a second supply voltage minus a second
threshold, and when the excitation signal comprises a voltage
amplitude that is less than a signal integrity threshold.
10. The device of claim 1, wherein, to determine whether the
excitation signal is outside of the threshold band of voltages, the
circuitry is configured to: determine a maximum voltage of the
excitation signal during a predetermined period of time; and
determine a minimum voltage of the excitation signal during the
predetermined period of time.
11. The device of claim 10, wherein the circuitry is further
configured to: output, to controller circuitry, an indication of
the maximum voltage and an indication of the minimum voltage; and
receive, from the controller circuitry, an indication of the second
gain value, wherein the controller circuitry generates the second
gain value based on the maximum voltage, the minimum voltage, or
both the maximum voltage and the minimum voltage.
12. The device of claim 10, wherein the circuitry is configured to
determine the second gain value based on the maximum voltage, the
minimum voltage, or both the maximum voltage and the minimum
voltage.
13. The device of claim 1, wherein the one or more sensing coils
comprises a sine sensing coil and a cosine sensing coil and wherein
the second gain value is generated based further on a first
amplitude of a sine sensing signal at the sine sensing coil, a
second amplitude of a cosine sensing signal at the cosine sensing
coil, or both the first amplitude and the second amplitude.
14. The device of claim 1, wherein, to amplify the carrier signal
using the first gain value, the circuitry is configured to output
the carrier signal into an input of a programmable operation
amplifier of the circuitry and set a gain of the programmable gain
operation amplifier to the first gain value; and wherein, to
amplify the carrier signal using the second gain value, the
circuitry is configured to output the carrier signal into the input
of the programmable gain operation amplifier and set the gain of
the programmable operation amplifier to the second gain value.
15. The device of claim 14, wherein the circuitry is formed in a
single integrated circuit.
16. A method for excitation of a resolver comprising an excitation
coil and one or more sensing coils, the method comprising:
amplifying, by circuitry, a carrier signal using a first gain value
to generate an excitation signal for output to the excitation coil
of the resolver; determining, by the circuitry, whether the
excitation signal is outside of a threshold band of voltages; and
amplifying, by the circuitry, the carrier signal using a second
gain value, wherein the second gain value is determined based on
whether the excitation signal is outside of the threshold band of
voltages.
17. A system for excitation of a resolver comprising an excitation
coil and one or more sensing coils, the system comprising:
excitation circuitry configured to: amplify a carrier signal using
a first gain value to generate an excitation signal for output to
the excitation coil of the resolver; determine whether the
excitation signal is outside of a threshold band of voltages;
output an indication of whether the excitation signal is outside of
the threshold band of voltages; and controller circuitry circuit
configured to generate a second gain value in response to the
indication of whether the excitation signal is outside of the
threshold band of voltages, wherein the excitation circuitry is
configured to amplify the carrier signal using the second gain
value.
18. The system of claim 17, wherein the indication of whether the
excitation signal is outside of the threshold band of voltages
comprises a high rail detection signal indicating whether the
excitation signal is in an upper distortion zone and a low rail
detection signal indicating whether the excitation signal is in a
lower distortion zone; and wherein the controller circuitry is
configured to generate the second gain value based on the high rail
detection signal, the low rail detection signal, or both the high
rail detection signal and the low rail detection signal.
19. The system of claim 17, wherein the indication of whether the
excitation signal is outside of the threshold band of voltages
comprises an indication of a maximum voltage of the excitation
signal during a predetermined period of time and an indication of a
minimum voltage of the excitation signal during the predetermined
period of time; and wherein the controller circuitry circuit is
configured to generate the second gain based on the maximum
voltage, the minimum voltage, or both the maximum voltage and the
minimum voltage.
20. The system of claim 17, wherein, to amplify the carrier signal
using the first gain value, the excitation circuitry is configured
to output the carrier signal into an input of a programmable
operation amplifier of the excitation circuitry and set a gain of
the programmable operation amplifier to the first gain value; and
wherein, to amplify the carrier signal using the second gain value,
the excitation circuitry is configured to output the carrier signal
into the input of the programmable operation amplifier and set the
gain of the programmable operation amplifier to the second gain
value.
Description
TECHNICAL FIELD
[0001] This disclosure relates to excitation for a resolver
configured to provide an angular feedback and/or positional
feedback for a motor, such as an AC motor or a brushless DC (BLDC)
motor.
BACKGROUND
[0002] A motor drive system may use angular feedback and/or a
positional feedback in order to efficiently and accurately drive
the motor. A resolver may include an excitation coil, a sine
sensing coil, and a cosine sensing coil. The excitation coil may be
located on a rotor of the resolver. As the rotor of the resolver
spins, the excitation coil may induce a current into the sine
sensing coil and cosine sensing coil. The sine sensing coil and
cosine sensing coil may be oriented 90 degrees from one another and
produce a vector position. The motor drive system may read the
vector position generated by the resolver to determine the angular
feedback and/or positional feedback of the motor. The motor drive
system may drive the motor using the determined angular feedback
and/or positional feedback of the motor.
SUMMARY
[0003] In general, this disclosure is directed to techniques for
improving a signal-to-noise ratio (SNR) for signals of a resolver.
Circuitry may be configured to amplify a carrier signal to generate
an excitation signal for output to the excitation coil of the
resolver with a gain value such that the excitation signal is
within a threshold band of voltages. For instance, the circuitry
may be configured to amplify a carrier signal to generate an
excitation signal that corresponds to a maximum gain within a
threshold band of voltages.
[0004] In one example, a device for excitation of a resolver
comprising an excitation coil and one or more sensing coils
includes circuitry configured to amplify a carrier signal using a
first gain value to generate an excitation signal for output to the
excitation coil of the resolver and determine whether the
excitation signal is outside of a threshold band of voltages. The
circuitry is further configured to amplify the carrier signal using
a second gain value, wherein the second gain value is generated
based on whether the excitation signal is outside of the threshold
band of voltages.
[0005] In another example, a method for excitation of a resolver
comprising an excitation coil and one or more sensing coils
includes amplifying, by circuitry, a carrier signal using a first
gain value to generate an excitation signal for output to the
excitation coil of the resolver and determining, by the circuitry,
whether the excitation signal is outside of a threshold band of
voltages. The method further comprises amplifying, by the
circuitry, the carrier signal using a second gain value, wherein
the second gain value is determined based on whether the excitation
signal is outside of the threshold band of voltages.
[0006] In another example, a system for excitation of a resolver
comprising an excitation coil and one or more sensing coils
includes excitation circuitry and controller circuitry. The
excitation circuitry is configured to amplify a carrier signal
using a first gain value to generate an excitation signal for
output to the excitation coil of the resolver and determine whether
the excitation signal is outside of a threshold band of voltages.
The excitation circuitry is further configured to output an
indication of whether the excitation signal is outside of the
threshold band of voltages. The controller circuitry circuit is
configured to generate a second gain value in response to the
indication of whether the excitation signal is outside of the
threshold band of voltages. The excitation circuitry is further
configured to amplify the carrier signal using the second gain
value.
[0007] In one example, an apparatus for excitation of a resolver
comprising an excitation coil and one or more sensing coils
includes means for amplifying a carrier signal using a first gain
value to generate an excitation signal for output to the excitation
coil of the resolver and means for determining whether the
excitation signal is outside of a threshold band of voltages. The
apparatus further comprises means for amplifying the carrier signal
using a second gain value, wherein the second gain value is
determined based on whether the excitation signal is outside of the
threshold band of voltages.
[0008] Details of these and other examples are set forth in the
accompanying drawings and the description below. Other features,
objects, and advantages will be apparent from the description and
drawings, and from the claims.
BRIEF DESCRIPTION OF DRAWINGS
[0009] FIG. 1 is a block diagram illustrating an example system
configured for excitation of a resolver, in accordance with one or
more techniques of this disclosure.
[0010] FIG. 2 is a conceptual diagram illustrating an example of
controller circuitry and an amplifier configured for excitation of
a resolver, in accordance with one or more techniques of this
disclosure.
[0011] FIG. 3A is a conceptual diagram illustrating an example
resolver, in accordance with one or more techniques of this
disclosure.
[0012] FIG. 3B is a graph illustrating an example of an excitation
signal, in accordance with one or more techniques of this
disclosure.
[0013] FIG. 3C is a graph illustrating an example of a cosine
excitation signal, in accordance with one or more techniques of
this disclosure.
[0014] FIG. 3D is a graph illustrating an example of a sine
excitation signal, in accordance with one or more techniques of
this disclosure.
[0015] FIG. 3E is a conceptual diagram illustrating an example of a
rotation angle of a motor in relation to a sine sensing signal and
a cosine sensing signal, in accordance with one or more techniques
of this disclosure.
[0016] FIG. 4 is a conceptual diagram illustrating an example of a
resolver exciter interface, in accordance with one or more
techniques of this disclosure.
[0017] FIG. 5 is a graph illustrating an example of an excitation
signal, an upper distortion zone, and a lower distortion zone, in
accordance with one or more techniques of this disclosure.
[0018] FIG. 6 is a circuit diagram illustrating first example
circuitry configured to determine whether an excitation signal is
outside of a threshold band of voltages, in accordance with one or
more techniques of this disclosure.
[0019] FIG. 7 is a graph illustrating an example of an excitation
signal, a high rail detection signal, and a low rail detection
signal, in accordance with one or more techniques of this
disclosure.
[0020] FIG. 8 is a circuit diagram illustrating second example
circuitry to determine whether the excitation signal is outside of
the threshold band of voltages, in accordance with one or more
techniques of this disclosure.
[0021] FIG. 9 is a conceptual diagram illustrating an example of
controller circuitry configured to generate a digital carrier
signal for excitation of a resolver, in accordance with one or more
techniques of this disclosure.
[0022] FIG. 10 is a conceptual diagram illustrating an example of
controller circuitry for excitation of a resolver and resolver
digital circuit configured to generate a digital carrier signal, in
accordance with one or more techniques of this disclosure.
[0023] FIG. 11 is a flow diagram illustrating a start-up sequence
to optimize the carrier amplitude prior to operating a motor in a
steady-state operation, in accordance with this disclosure.
[0024] FIG. 12 is a flow diagram illustrating a process to maintain
the optimum configuration during a steady-state operation, in
accordance with this disclosure.
[0025] FIG. 13 is a flow diagram illustrating a method for
excitation of a resolver comprising an excitation coil and one or
more sensing coils, in accordance with this disclosure.
DETAILED DESCRIPTION
[0026] The amplitude of an excitation carrier signal at an
excitation coil of a resolver may not directly influence the result
of an angle calculation for a motor because the amplitude may
cancel out due to a division operation. As such, in order to
improve the signal-to-noise ratio (SNR), especially for the zero
crossing moments when one amplitude is low, the carrier signal
voltage may set to be as large as possible. However, the amplitude
may be controlled and kept sufficiently low, in order to avoid any
rail saturation effects of the amplifier because the resulting
saturation distortions may cause significant disturbances in the
excitation signal which may corrupt the angle calculation.
Accordingly, some systems may use an amplitude of the excitation
carrier signal that is as large as possible and safely below
distortion limits of the amplifier.
[0027] To avoid distortion, some systems may use discrete devices.
For example, a system may use an operational amplifier with a gain
set by external resistors that are carefully selected by a
technician to precisely define the gain, which may rely on a cost
intensive end-of-line calibration. The cost intensive end-of-line
calibration may significantly add to a cost and size of a resulting
product. Moreover, due to the existing uncertainties, the system
may use a guard-band comprising relatively large margins at all
times in order to avoid the generation of distortions in the
carrier amplifier. As a result, a usable excitation voltage range
may be reduced to account for uncertainties in the system.
[0028] In accordance with the techniques of the disclosure, a
system may include elements for a resolver excitation voltage
generation system which may allow the system itself to recognize
that saturation distortions are present in the system. Using the
information on whether the saturation distortion are present, the
system (e.g. a micro-controller) can adjust a gain for amplifying
the excitation signal such that a voltage amplitude represents an
optimum combination of a highest possible amplitude that is free of
saturation effects.
[0029] For example, the system may include two comparators which
may monitor a voltage of an excitation signal and compare the
voltage of the excitation signal to thresholds close to the supply
voltage rails (e.g., a high voltage rail and a low voltage rail).
When the voltage of the excitation signal is outside one of these
thresholds, the comparators may indicate that a saturation
distortion has occurred to a digital circuit.
[0030] In some examples, analog peak detection circuits may be used
to capture a maximum and minimum amplitude measured at the
excitation signal during a defined period of time. In this way, the
analog peak detection circuitry may measure peak level voltages
using a sampling analog-to-digital converter (ADC) either by
multiplexing both (or more) values into one ADC or by individual
ADCs. Circuitry may use the digitized values for further digital
processing and provide the digitized values, for example, to
controller circuitry, to indicate whether a saturation distortion
has occurred.
[0031] FIG. 1 is a block diagram illustrating an example system
configured for excitation of a resolver 104, in accordance with one
or more techniques of this disclosure. As illustrated in this
example of FIG. 1, system 100 may include circuitry 102 and
resolver 104. Circuitry 102 may be configured for excitation of an
excitation coil 120. Circuitry 102 may include an amplifier 110 and
an excitation signal detector 112. Circuitry 102 may include analog
circuitry, digital circuitry, or analog circuitry and digital
circuitry. Circuitry 102 may be formed in a single integrated
circuit. For example, circuitry 102 may include amplifier 110
comprising a programmable operation amplifier and excitation signal
detector 112 such that amplifier 110 may operate with a
programmable gain without resistors external to the single
integrated circuitry formed by circuitry 102.
[0032] Amplifier 110 may be configured to amplify a carrier signal
to generate an excitation signal for output to excitation coil 120
of resolver 104. Amplifier 110 may be formed using an operational
amplifier, for example, a programmable gain operational amplifier.
As described further herein, the carrier signal may be generated
using a carrier generator or another device. The gain value may be
generated by controller circuitry. In some examples, circuitry 102
may generate the gain value.
[0033] Excitation signal detector 112 may be configured to
determine whether the excitation signal is outside of a threshold
band of voltages. For example, excitation signal detector may be
configured to output an indication of whether the excitation signal
is outside of the threshold band of voltages. Excitation signal
detector 112 may include one or more comparators configured to
indicate whether the excitation signal comprises a voltage greater
than a first rail and/or a voltage less than a second rail (e.g., a
ground rail). In some examples, excitation signal detector 112 may
be configured to determine a maximum voltage of the excitation
signal during a predetermined period of time and/or determine a
minimum voltage of the excitation signal during the predetermined
period of time. Excitation signal detector 112 may output the
indication of whether the excitation signal is outside of the
threshold band of voltages to controller circuitry. In some
examples, excitation signal detector 112 may output the indication
of whether the excitation signal is outside of the threshold band
of voltages to another component of circuitry 102.
[0034] In accordance with the techniques of the disclosure,
amplifier 110 may amplify a carrier signal using a first gain value
to generate an excitation signal for output to the excitation coil
of resolver 104. For example, amplifier 110 may be configured to
output the carrier signal into an input of a programmable operation
amplifier of amplifier 110 and set a gain of the programmable gain
operation amplifier to the first gain value.
[0035] Excitation signal detector 112 may determine whether the
excitation signal is outside of a threshold band of voltages. For
example, excitation signal detector 112 may determine whether the
excitation signal is outside of a threshold band of voltages using
one or more comparators. In some examples, excitation signal
detector 112 may determine whether the excitation signal is outside
of a threshold band of voltages using one or more peak
detectors.
[0036] Amplifier 110 may amplify the carrier signal using a second
gain value. For example, amplifier 110 may be configured to output
the carrier signal into an input of a programmable operation
amplifier of amplifier 110 and set a gain of the programmable gain
operation amplifier to the second gain value. The second gain value
may be generated based on whether the excitation signal is outside
of the threshold band of voltages. Circuitry 102 may itself
generate the second gain value based on whether the excitation
signal is outside of the threshold band of voltages. For example,
circuitry 102 may generate the second gain to be less than the
first gain when a voltage of the excitation signal exceeds a
combination of a first supply voltage and a first threshold or when
the voltage of the excitation signal is less than a second supply
voltage minus a second threshold.
[0037] In some examples, circuitry 102 may output an indication of
the excitation signal is outside of the threshold band of voltages
to other circuitry, which may generate the second gain. For
example, circuitry 102 may output, to controller circuitry, an
indication that the excitation signal is outside of the threshold
band of voltages. The controller circuitry may generate the second
gain value based on whether the excitation signal is outside of the
threshold band of voltages. For example, the controller circuitry
may generate the second gain to be less than the first gain when
the excitation signal is outside of the threshold band of voltages.
In this example, circuitry 102 may receive, from the controller
circuitry, an indication of the second gain value.
[0038] FIG. 2 is a conceptual diagram illustrating an example of
controller circuitry 206 and an amplifier 210 configured for
excitation of a resolver 204, in accordance with one or more
techniques of this disclosure. In the example of FIG. 2, resolver
204 may include an excitation coil 220, a sine sensing coil 222,
and a cosine sensing coil 224.
[0039] High power AC motor or a brushless DC (BLDC) motor drive
applications may use an angular feedback and positional feedback in
order to efficiently and accurately drive a motor. Some systems may
use optical encoders, hall sensors, or resolvers for positional
feedback. Examples described herein may use resolver 204 for
positional feedback. Resolver 204 may be used, for example, when
environmental or longevity are challenging and extensive. Resolver
204 may act like a transformer with one primary coil (e.g.,
excitation coil 220) and two secondary coils (e.g., sine sensing
coil 222 and cosine sensing coil 224). Excitation coil 220 may be
rigidly connected to a rotor of resolver 204. As the rotor of
resolver 204 spins, excitation coil 220 may induce a current into
sine sensing coil 222 and cosine sensing coil 224. Sine sensing
coil 222 and cosine sensing coil 224 may be oriented 90 degrees
from one another and produce a vector position read by controller
circuitry 206 (e.g., a resolver to digital converter chip).
Excitation coil 220 may have a very low DC resistance (e.g., less
than 100.OMEGA.), which may result in a current sink and a current
source of up to 200 mA from amplifier 210 (e.g., an excitation
driver).
[0040] Controller circuitry 206 may include a carrier generator 240
configured to generate a carrier signal. The carrier signal may be
output as a low carrier signal and a high carrier signal. Channel A
242 may be configured to receive a sine sensing signal from sine
sensing coil 222. Rectifier 244 may be configured to rectify the
sine sensing signal with the carrier frequency of the carrier
signal to generate a rectified sine signal. Integrator 246 may be
configured to integrate half-cycles of the carrier frequency to
apply filtering of the rectified sine signal to generate an
integrated sine signal. Similarly, channel B 252 may be configured
to receive a cosine sensing signal from cosine sensing coil 224.
Rectifier 254 may be configured to rectify the cosine sensing
signal with the carrier frequency of the carrier signal to generate
a rectified cosine signal. Integrator 256 may be configured to
integrate half-cycles of the carrier frequency to apply filtering
of the rectified cosine signal to generate an integrated cosine
signal.
[0041] Controller circuitry 206 may include a microcontroller
formed on a single integrated circuit containing a processor core,
memory, inputs, and outputs. For example, controller circuitry 206
may include one or more processors, including one or more
microprocessors, digital signal processors (DSPs), application
specific integrated circuits (ASICs), field programmable gate
arrays (FPGAs), or any other equivalent integrated or discrete
logic circuitry, as well as any combinations of such components.
The term "processor" or "processing circuitry" may generally refer
to any of the foregoing logic circuitry, alone or in combination
with other logic circuitry, or any other equivalent circuitry.
[0042] Amplifier 210 may include power stage 230 and power stage
232. Power stage 230 may be configured to amplify the high carrier
signal output by carrier generator 240. Power stage 232 may be
configured to amplify the low carrier signal output by carrier
generator 240. As described further herein, the combination of the
outputs of power stage 230 and power stage 232 may generate the
excitation signal for output to excitation coil 220 of resolver
204.
[0043] In accordance with the techniques of the disclosure,
amplifier 210 may, rather than rely on external resistors to define
a fixed gain that are selected by a technician, be configured to
modify a gain applied to the high carrier signal and the low
carrier signal such that the excitation signal is generated at a
maximum amplitude that is free of saturation effects. In this way,
system 200 may generate the excitation signal with a highest SNR,
which may improve an accuracy of the calculating the angle of
resolver 204.
[0044] FIG. 3A is a conceptual diagram illustrating an example
resolver 304, in accordance with one or more techniques of this
disclosure. Resolver 304 receives an excitation signal at nodes R1
and R2 for an exciter coil to deliver the driving voltage. Resolver
304 may output a sine sensing signal representing the excitation
signal multiplied by sin(.PHI.) at nodes S1 and S2 and a cosine
sensing signal representing the excitation signal multiplied by
cos(.PHI.) at nodes S3 and S4, with .PHI.=rotation angle of a
motor). The sine sensing signal and/or the cosine sensing signal
may be directly handled by a controller circuitry.
[0045] FIG. 3B is a graph illustrating an example of an excitation
signal 360, in accordance with one or more techniques of this
disclosure. Excitation signal 360 may be generated by amplifying,
by amplifier 210, a carrier signal generated by carrier generator
240. Excitation signal 360 may be received at nodes R1 and R2 of
resolver 304.
[0046] FIG. 3C is a graph illustrating an example of a sine sensing
signal 362, in accordance with one or more techniques of this
disclosure. Sine sensing signal 362 may be output at nodes S1 and
S2 of resolver 304.
[0047] FIG. 3D is a graph illustrating an example of a cosine
sensing signal 364, in accordance with one or more techniques of
this disclosure. Cosine sensing signal 364 may be output at nodes
S3 and S4 of resolver 304.
[0048] FIG. 3E is a conceptual diagram illustrating an example of a
rotation angle of a motor in relation to sine sensing signal 362
and cosine sensing signal 364, in accordance with one or more
techniques of this disclosure. As shown, the position (.PHI.) may
be determined by applying an arctan function (e.g., an inverse of a
tangent function) of the result of sine sensing signal 362 divided
by the cosine sensing signal 364.
[0049] FIG. 4 is a conceptual diagram illustrating an example of a
resolver exciter interface, in accordance with one or more
techniques of this disclosure. System 400 may include a resolver
exciter interface (IF) 402, a resolver 404, and a microcontroller
(C) 406.
[0050] Microcontroller 406 may generate a carrier signal. Resolver
exciter interface 402 may receive the carrier signal at an analog
input stage and low-pass filter (LPF), and apply an analog output
amplifier using bandwidth, gain, and offset configuration
information to generate an excitation signal. Resolver 404 receives
the excitation signal and generates, based on a position of a rotor
of resolver 404 that is rigidly coupled to a rotor of a motor, a
sine sensing signal (e.g., (carrier*sin(.PHI.))/2) and a cosine
sensing signal (e.g., (carrier*cos(.PHI.))/2)). In this example,
microcontroller 406 may read, with an ADC (e.g., a sigma-delta
ADC), the sine sensing signal and the cosine sensing signal to
determine the position of the rotor of resolver 404.
Microcontroller 406 may drive a motor using the position of the
rotor of resolver 404. As shown, system 400 may be configured to
include additional circuitry. For instance, system 400 may include
a voltage supply to provide a boosted voltage and a serial
peripheral interface (SPI) for communication between
microcontroller 406 and resolver exciter interface 402.
[0051] Microcontroller 406 may include a microcontroller formed on
a single integrated circuit containing a processor core, memory,
inputs, and outputs. For example, Microcontroller 406 may include
one or more processors, including one or more microprocessors,
DSPs, ASICs, FPGAs, or any other equivalent integrated or discrete
logic circuitry, as well as any combinations of such
components.
[0052] FIG. 5 is a graph illustrating an example of an excitation
signal 502, an upper distortion zone 512, and a lower distortion
zone 520, in accordance with one or more techniques of this
disclosure. FIG. 5 shows a visualization of excitation signal 502
that is distortion free.
[0053] Some systems may use an operational amplifier with a single
gain set by external resistors, where the single gain is set to
include relatively large margins to account for uncertainties in
the system. Accordingly, such systems may include an upper margin
514 and a lower margin 518 that are relatively large to help to
avoid the generation of distortions in excitation signal 502 (e.g.,
the excitation signal 502 extending into the upper distortion band
512 and/or the lower distortion band 520). The combination of upper
distortion zone 512 and upper margin 514 may be referred to herein
as an "upper guard-band." Similarly, the combination of lower
distortion zone 520 and lower margin 518 may be referred to herein
as a "lower guard-band." However, systems relying on margin 514 and
lower margin 518 that are relatively large may reduce a usable
excitation signal range (illustrated as "operation range").
[0054] In accordance with the techniques of the disclosure, a
device (e.g., circuitry 102) for excitation of a resolver may
amplify a carrier signal using a gain that is generated based on
whether excitation signal 502 is outside of a threshold band of
voltages (e.g., outside the upper guard-band and the lower
guard-band). For example, the device may lower a gain when
excitation signal 502 is within the upper guard-band formed by
upper distortion zone 512 and upper margin 514 and/or the lower
guard-band formed by lower distortion zone 520 and lower margin
518. In some examples, the device may increase the gain when
excitation signal 502 is not within the upper guard-band and the
lower guard-band. Setting the gain based on whether excitation
signal 502 is outside of the threshold band of voltages may help to
reduce the size of upper margin 514 and lower margin 518 compared
to systems that rely on a single gain value or may allow the device
to omit upper margin 514 and lower margin 518. Reducing the size of
upper margin 514 and lower margin 518 or omitting upper margin 514
and lower margin 518 may increase a size of the operating range for
excitation signal 502, which may improve the signal-to-noise ratio
(SNR) for excitation signal 502.
[0055] FIG. 6 is a circuit diagram illustrating first example
circuitry 612 configured to determine whether an excitation signal
is outside of a threshold band of voltages, in accordance with one
or more techniques of this disclosure. Circuitry 612 may be
included in excitation signal detector 112 of FIG. 1. In the
example of FIG. 6, circuitry 612 may include a first comparator
670, first guard-band element 672, and a second comparator 674, and
second guard-band element 676. Digital filter and evaluation
circuitry 606 may be an example of controller circuitry.
[0056] In accordance with the techniques of the disclosure,
circuitry 612 may help to ensure a voltage of the excitation signal
does not comprise saturation distortions. For example, circuitry
612 may include first comparator 670 and second comparator 674,
which may help to allow a system controller (e.g., a
micro-controller) to detect the presence of a distortions and/or to
detect that the system is entering an operating area in which such
distortions are likely to occur.
[0057] FIG. 6 shows an example of an output stage of a resolver
excitation output amplifier (e.g., with a programmable gain). At
the output, circuitry 612 includes first comparator 670 and second
comparator 674 to monitor the excitation signal and compare a
voltage of the excitation signal to thresholds close to the supply
voltage rails. In the example of FIG. 6, VPR2_P may represent a
high supply and gnda (e.g., ground) may represent a low supply
voltage. When the excitation voltage extends beyond the high supply
provided by VPR2_P and/or the low supply voltage provided by gnda,
first comparator 670 and/or second comparator 674 may indicate that
an excitation signal is outside of a threshold band of voltages to
digital filter and evaluation circuitry 606.
[0058] Circuitry 612 may determine whether a voltage of the
excitation signal exceeds a combination of a first supply voltage
(e.g., VPR2P) and a first guard-band voltage. Similarly, circuitry
612 may determine whether the voltage of the excitation signal is
less than a second supply voltage (e.g., gnda) minus a second
guard-band voltage.
[0059] For example, circuitry 612 may be configured to output the
excitation signal to a first input (e.g., a negative terminal) of
first comparator 670. Circuitry 612 may be configured to output a
first supply voltage to a second input (e.g., a positive terminal)
of first comparator 670. Circuitry 612 may be configured to apply,
with first guard-band element 672, a first guard-band voltage
(e.g., 1.2 V) that offsets a voltage at the first input of first
comparator 670 or a voltage at the second input of first comparator
670. For instance, as shown in FIG. 6, first guard-band element 672
generates first guard-band voltage (e.g., 200 mV) to offset a
voltage at the first input of first comparator 670.
[0060] First guard-band element 672 may comprise a resistor and a
reference constant current source to generate a voltage drop. In
some examples, first guard-band element 672 may comprise a bias
current and a bipolar diode to generate a reference voltage drop.
First guard-band element 672 may comprise a bias current and a
metal-oxide-semiconductor (MOS) diode to generate a MOS threshold
based reference current drop. However, first guard-band element 672
may generate a first guard-band voltage using any other means of
generating a constant reference voltage drop such as, for example,
bandgaps, reference regulators, or another guard-band element.
[0061] Similarly, circuitry 612 may be configured to output the
excitation signal to a first input (e.g., a positive terminal) of
second comparator 674. Circuitry 612 may be configured to output a
second supply voltage to a second input (e.g., a negative terminal)
of second comparator 674. Circuitry 612 may be configured to apply,
with second guard-band element 676, a second guard-band voltage
(e.g., 200 mV) that offsets a voltage at the first input of second
comparator 674 or a voltage at the second input of second
comparator 674. For instance, as shown in FIG. 6, second guard-band
element 676 generates second guard-band voltage (e.g., 200 mV) to
offset a voltage at the second input of second comparator 674.
[0062] Second guard-band element 676 may comprise a resistor and a
reference constant current source to generate a voltage drop. In
some examples, second guard-band element 676 may comprise a bias
current and a bipolar diode to generate a reference voltage drop.
Second guard-band element 676 may comprise a bias current and a MOS
diode to generate a MOS threshold based reference current drop.
However, second guard-band element 676 may generate a second
guard-band voltage using any other means of generating a constant
reference voltage drop such as, for example, bandgaps, reference
regulators, or another guard-band element.
[0063] First comparator 670 may output, to controller circuitry
(e.g., digital filter and evaluation circuitry 606) a high rail
detection signal (e.g., rail_det_h) indicating that the excitation
signal is in an upper distortion zone in response to determining
that the excitation signal exceeds the threshold band of voltages.
Similarly, second comparator 674 may output, to the controller
circuitry, a low rail detection signal (e.g., rail_det_l)
indicating that the excitation signal is in a lower distortion zone
in response to determining that the excitation signal is less than
the threshold band of voltages.
[0064] Digital filter and evaluation circuitry 606 may perform
signal processing as described further below. Digital filter and
evaluation circuitry 606 may include a blanking time counter to
suppress error indications right after start-up or enabling the
amplifier. In some examples, digital filter and evaluation
circuitry 606 may perform filtering to allow for short period
violations (e.g., without error indication, e.g. for spikes or
voltage drops). Digital filter and evaluation circuitry 606 may
perform latching in order to remember violation events beyond one
period. Digital filter and evaluation circuitry 606 may perform any
combination of blanking time counting, filtering, and/or
latching.
[0065] FIG. 7 is a graph illustrating an example of an excitation
signal 702, a high rail detection signal 704, and a low rail
detection signal 706, in accordance with one or more techniques of
this disclosure. FIG. 7 shows an example excitation signal 702,
which is exceeding the limits of the linear operation range (e.g.,
within upper distortion zone 712 and/or lower distortion zone 720)
of a power amplifier with programmable gain.
[0066] In the example of FIG. 7, a first comparator (e.g., first
comparator 670) may output, to controller circuitry high rail
detection signal 704 (e.g., rail_det_h) indicating that the
excitation signal is in an upper distortion zone (e.g., a logical
`1`) in response to determining that the excitation signal exceeds
the threshold band of voltages. Similarly, a second comparator
(e.g., second comparator 674) may output, to the controller
circuitry, a low rail detection signal (e.g., rail_det_l)
indicating that the excitation signal is in a lower distortion zone
(e.g., a logical `1`) in response to determining that the
excitation signal is less than the threshold band of voltages.
[0067] FIG. 8 is a circuit diagram illustrating second example
circuitry 812 to determine whether an excitation signal is outside
of the threshold band of voltages, in accordance with one or more
techniques of this disclosure. As shown, circuitry 812 may include
a high peak detector 880, low peak detector 882, and ADC 884.
Digital filter and evaluation circuitry 806 may be an example of
controller circuitry.
[0068] In the example of FIG. 8, high peak detector 880 may be
configured to capture a maximum amplitude measured at the output of
the power amplifier during a defined period of time (e.g., using a
discharge resistor of high peak detector 880 arranged in parallel
with a capacitor). Similarly, low peak detector 882 may be
configured to capture a minimum amplitude measured at the output of
the power amplifier during the defined period of time (e.g., using
a discharge resistor of low peak detector 882 arranged in parallel
with a capacitor).
[0069] ADC 884 may sample the capture maximum amplitude and minimum
amplitudes during the defined period of time. For example, ADC 884
may multiplex both (or more) of the maximum amplitude and minimum
amplitudes values into one ADC (as shown in FIG. 8) or by
individual ADCs (not shown). ADC 884 may generate digitized values
of the maximum amplitude and minimum amplitudes, which may be
subsequently used for further digital processing and provided to
digital filter and evaluation circuitry 806 for determining a
saturation indication (e.g., whether the excitation signal is
outside of the threshold band of voltages).
[0070] The techniques using a first comparator and a second
comparator illustrated in FIG. 6 and the techniques illustrated in
FIG. 8 may be used separately, or in combination, to monitor high
and low level saturations at the same time, or to monitor only one
supply rail. However, monitoring a high rail level and a low rail
level may allow for diagnosis in the case of common mode potential
(e.g., idle potential) faults.
[0071] In accordance with the techniques of the disclosure, high
peak detector 880 may determine a maximum voltage of the excitation
signal during a predetermined period of time. ADC 884 may sample
one or more maximum amplitude values generated by high peak
detector 880 to generate an indication of a maximum voltage. ADC
884 may output, to controller circuitry, an indication of the
maximum voltage.
[0072] Similarly, low peak detector 882 may determine a minimum
voltage of the excitation signal during the predetermined period of
time. ADC 884 may sample one or more minimum amplitudes values
generated by low peak detector 882 to generate an indication of a
minimum voltage. ADC 884 may output, to digital filter and
evaluation circuitry 806, an indication of the minimum voltage.
[0073] Circuitry 812 (e.g., an amplifier of circuitry 812) may
receive, from digital filter and evaluation circuitry 806, an
indication of a gain value (e.g., a second gain value). For
instance, digital filter and evaluation circuitry 806 may generate
the gain value based on the maximum voltage, the minimum voltage,
or both the maximum voltage and the minimum voltage. In some
examples, however, circuitry 812 may be configured to determine a
gain value (e.g., a second gain value) based on the maximum
voltage, the minimum voltage, or both the maximum voltage and the
minimum voltage. In some examples, circuitry 812 may determine the
gain value and digital filter and evaluation circuitry 806 may be
bypassed.
[0074] FIG. 9 is a conceptual diagram illustrating an example of
controller circuitry 906 configured to generate a digital carrier
signal for excitation of a resolver 904, in accordance with one or
more techniques of this disclosure. In the example of FIG. 9,
controller circuitry 906 may receive a sine sensing signal and a
cosine sensing signal from resolver 904. In this example,
controller circuitry 906 may determine a position for a motor using
the sine sensing signal and a cosine sensing signal. Controller
circuitry 906 may generate a digital carrier signal. In the example
of FIG. 9, controller circuitry 906 may receive a rail detection
indication (e.g., rail_det_h and/or rail_det_l) and generate the
carrier gain setting based on the rail detection indication. In
some examples, however, controller circuitry 906 may receive an
indication of a peak (e.g., digitized values of the maximum
amplitude and minimum amplitudes) and generate the carrier gain
setting based on the digitized values of the maximum amplitude and
minimum amplitudes.
[0075] In addition, or alternatively, to using comparators (e.g.,
see FIG. 6) and/or using peak detectors (see FIG. 8), controller
circuitry 906 may be configured to generate a gain value (e.g., a
second gain value) for the excitation signal based on a first
amplitude of the sine sensing signal at a sine sensing coil of
resolver 904, a second amplitude of a cosine sensing signal at a
cosine sensing coil of resolver 904, or both the first amplitude
and the second amplitude.
[0076] Circuitry 902 may include a carrier amplifier 930 configured
to generate an excitation signal based on the carrier gain setting.
For example, carrier amplifier 930 may be configured to output the
carrier signal into an input of a programmable operation amplifier
of carrier amplifier 930 and set a gain of the programmable gain
operation amplifier to the carrier setting gain value.
[0077] Controller circuitry 906 may host and use information
relating to the excitation carrier amplitude in order to optimize
an operation of resolver 904. The feedback information provided by
the rail detection circuit of circuitry 902 may allow controller
circuitry 906 to adjust the carrier amplitude to the achievable or
reasonable maximum and hence to tune resolver 904 to an operating
point with maximum signal integrity and best accuracy.
Additionally, controller circuitry 906 may adjust an amplitude of
the excitation signal to avoid voltages that may result in harmonic
distortions in the excitation signal, excessive power dissipation
in the excitation signal, or both harmonic distortions and
excessive power dissipation in the excitation signal.
[0078] Controller circuitry 906 may include a microcontroller
formed on a single integrated circuit containing a processor core,
memory, inputs, and outputs. For example, controller circuitry 906
may include one or more processors, including one or more
microprocessors, DSPs, ASICs, FPGAs, or any other equivalent
integrated or discrete logic circuitry, as well as any combinations
of such components.
[0079] FIG. 10 is a conceptual diagram illustrating an example of
controller circuitry 1006 for excitation of a resolver 1004 and
resolver digital circuitry 1007 configured to generate a digital
carrier signal, in accordance with one or more techniques of this
disclosure.
[0080] In contrast to FIG. 9, system 100 illustrated in FIG. 10 can
use any automotive (or non-automotive) micro-controller to
implement controller circuitry 1006 in combination with resolver
digital circuitry 1007 (e.g., a resolver-to-digital converter
device). Resolver digital circuitry 1007 may generate a low voltage
carrier signal and calculate a rotational angle based on a sine
sensing signal and a cosine sensing signal. Controller circuitry
1006 may retrieve a digital representation of the motor angle from
resolver digital circuitry 1007 by reading out dedicated data
registers.
[0081] In the example of FIG. 10, controller circuitry 1006 may
receive a rail detection indication (e.g., rail_det_h and/or
rail_det_l) and generate the carrier gain setting based on the rail
detection indication. In some examples, however, controller
circuitry 1006 may receive an indication of a peak (e.g., digitized
values of the maximum amplitude and minimum amplitudes) and
generate the carrier gain setting based on the digitized values of
the maximum amplitude and minimum amplitudes.
[0082] In addition, or alternatively, to using comparators (e.g.,
see FIG. 6) and/or using peak detectors (see FIG. 8), controller
circuitry 1006 may be configured to generate a gain value (e.g., a
second gain value) for the excitation signal based on a first
amplitude of the sine sensing signal at a sine sensing coil of
resolver 1004, a second amplitude of a cosine sensing signal at a
cosine sensing coil of resolver 1004, or both the first amplitude
and the second amplitude.
[0083] Circuitry 1002 may include a carrier amplifier 1030
configured to generate an excitation signal based on the carrier
gain setting. For example, carrier amplifier 1030 may be configured
to output the carrier signal into an input of a programmable
operation amplifier of carrier amplifier 1030 and set a gain of the
programmable gain operation amplifier to the carrier setting gain
value.
[0084] Controller circuitry 1006 may host and use information
relating to the excitation carrier amplitude in order to optimize
an operation of resolver 1004. The feedback information provided by
the rail detection circuit of circuitry 1002 may allow controller
circuitry 1006 to adjust the carrier amplitude to the achievable or
reasonable maximum and hence to tune resolver 1004 to an operating
point with maximum signal integrity and best accuracy.
Additionally, controller circuitry 1006 may adjust the carrier
amplitude to avoid excitation signal voltages that may result in
harmonic distortions in the excitation signal, excessive power
dissipation in the excitation signal, or both harmonic distortions
and excessive power dissipation in the excitation signal.
[0085] Controller circuitry 1006 may include a microcontroller
formed on a single integrated circuit containing a processor core,
memory, inputs, and outputs. For example, controller circuitry 1006
may include one or more processors, including one or more
microprocessors, DSPs, ASICs, FPGAs, or any other equivalent
integrated or discrete logic circuitry, as well as any combinations
of such components.
[0086] FIG. 11 is a flow diagram illustrating a start-up sequence
to optimize the carrier amplitude prior to a steady-state
operation, in accordance with this disclosure. FIG. 11 shows a
start-up sequence to optimize an amplitude of an excitation signal
prior to starting a motor.
[0087] In the example of FIG. 11, a system performs a start-up
resolver excitation (1102) and uses known parameters to calculate
an initial carrier gain setting (1104). For example, controller
circuitry may determine an initial amplitude for the excitation
signal based on a carrier signal configuration. The system may
configure a carrier generator and start carrier generation (1106).
The system may increase carrier gain (1108). The system may
determine whether a rail detection is reported (1110). For
instance, the system may determine whether the excitation voltage
exceeds a threshold band of voltages using techniques described in
FIG. 6. In response to no rail detection being reported ("NO" of
step 1110), the system returns to step 1108. In response to a rail
detection being reported ("YES" of step 1110), the system reverts
the carrier gain setting back to a last known carrier gain setting
without the rail detection event (1112) and starts an application
(1114).
[0088] That is, to determine a second gain value for starting the
application (e.g., operating in steady-state), circuitry 102 may be
configured to generate, during a start-up operation, the second
gain value to be greater than the first gain value when a voltage
of the excitation signal does not exceed a combination of a first
supply voltage and a first threshold and when the voltage of the
excitation signal is less than a second supply voltage minus a
second threshold (e.g., does not result in a rail detection
reported).
[0089] While the above example uses rail detection to determine
whether the excitation voltage exceeds a threshold band of
voltages, other examples, may determine whether the excitation
voltage exceeds a threshold band of voltages differently. For
example, a system may determine whether the excitation voltage
exceeds a threshold band of voltages using one or more peak
detectors (see FIG. 8).
[0090] FIG. 12 is a flow diagram illustrating a process to maintain
an optimum configuration during steady-state operation, in
accordance with this disclosure. FIG. 12 describes a strategy to
maintain a configuration during runtime. Optimum configuration may
need some re-adjustment because application parameters may vary
over time. During a run-time (e.g., during application running
1202), a system may try whenever the amplitude level of a sine
sensing signal and a cosine sensing signal are weak to increase an
amplitude of the excitation signal.
[0091] For example, the system may determine whether a rail
detection is reported (1204). For instance, the system may
determine whether the excitation voltage exceeds a threshold band
of voltages using techniques described in FIG. 6. In response to a
rail detection being reported ("YES" of step 1204), the system
reduces the carrier gain (1214) and returns to step 1204. In
response to no rail detection being reported ("NO" of step 1204),
the system checks a resolver output signal integrity (1206) and
determines whether the signal integrity is too weak (1208). The
system may determine the signal integrity threshold by monitoring
the excitation signal itself and/or comparing an amplitude of the
excitation signal to a minimum required amplitude. In some
examples, the system may determine the signal integrity by
monitoring the amplitude of one or more sensing signal(s) on the
sensing coils (e.g., sine sensing coil and cosine sensing coil).
For instance, circuitry 902 may determine the signal integrity by
monitoring the amplitude of one or more sensing signal(s) on the
sensing coils. In some examples, controller circuitry 906 may
determine the signal integrity by monitoring the amplitude of one
or more sensing signal(s) on the sensing coils. For instance,
controller circuitry 906 may determine the signal integrity using
information used for numeric algorithms related to the angle
computation.
[0092] In response to the signal integrity not being too weak ("NO"
of step 1208), the system returns to step 1204. In response to the
signal integrity being too weak ("YES" of step 1208), the system
increases the carrier gain 1210 and determines whether a shutdown
signal is received (1212). In response to not receiving a shutdown
signal ("NO" of step 1212), the system returns to step 1204. In
response to receiving a shutdown signal ("YES" of step 1212), the
system shuts down.
[0093] While the regulation principles described in FIGS. 11 and 12
are directed to comparator-based examples, which have been
discussed in FIG. 6, the regulation of the carrier signal amplitude
can be even simplified when using the ADC based examples presented
in FIG. 8. When using ADC based examples, the system could retrieve
real-time quantitative information about the current excitation
signal amplitude and can react accordingly. Retrieving real-time
quantitative information about the current excitation signal
amplitude may allow the system to react appropriately to variations
of the resolver excitation circuits supply voltage before the
excitation signal reaches the distortion region and/or boost the
amplitude of the excitation signal immediately when the supply
voltage recovers without "over-tuning" the excitation signal
amplitude as described above.
[0094] That is, to determine a second gain value, circuitry 102 of
FIG. 1 may be configured to generate, during a steady-state
operation of the circuitry, the second gain value to be greater
than the first gain value when a voltage of the excitation signal
does not exceed a combination of a first supply voltage and a first
threshold, when the voltage of the excitation signal is less than a
second supply voltage minus a second threshold (e.g., when no rail
detection is reported), and when the excitation signal comprises a
voltage amplitude that is less than a signal integrity threshold
(e.g., when the excitation signal is too weak).
[0095] FIG. 13 is a flow diagram illustrating a method for
excitation of a resolver comprising an excitation coil and one or
more sensing coils, in accordance with this disclosure. FIG. 13 is
discussed with reference to FIGS. 1-12 for example purposes only
although the techniques of FIG. 13 may be used with other systems
or devices.
[0096] In accordance with one or more techniques of this
disclosure, amplifier 110 may amplify a carrier signal using a
first gain value to generate an excitation signal for output to the
excitation coil of resolver 104 (1302). For example, amplifier 110
may be configured to output the carrier signal into an input of a
programmable operation amplifier of carrier amplifier 930 and set a
gain of the programmable gain operation amplifier to the carrier
setting gain value.
[0097] Excitation signal detector 112 may determine whether the
excitation signal is outside of a threshold band of voltages
(1304). For example, first comparator 670 may output, to controller
circuitry (e.g., digital filter and evaluation circuitry 606) a
high rail detection signal (e.g., rail_det_h) indicating that the
excitation signal is in an upper distortion zone in response to
determining that the excitation signal exceeds the threshold band
of voltages. Similarly, second comparator 674 may output, to the
controller circuitry, a low rail detection signal (e.g.,
rail_det_l) indicating that the excitation signal is in a lower
distortion zone in response to determining that the excitation
signal is less than the threshold band of voltages. In some
examples, ADC 884 may output, to controller circuitry, an
indication of a maximum voltage and/or a minimum voltage of an
excitation signal during a period of time.
[0098] Amplifier 110 may amplify the carrier signal using a second
gain value, wherein the second gain value is generated based on
whether the excitation signal is outside of the threshold band of
voltages (1306). For example, controller circuitry 906 may
determine the second gain value during a start-up operation as
described in FIG. 11. In some examples, controller circuitry 906
may determine the second gain value as described in FIG. 12 during
a steady-state operation. Controller circuitry 906 may, in some
examples, reduce the gain when the amplitude is higher than a
maximum threshold value and reduce the gain when the amplitude is
less than a minimum threshold value.
[0099] In some examples, circuitry 102 may determine the second
gain value. For instance, circuitry 102 may determine the second
gain value during a start-up operation as described in FIG. 11
and/or circuitry 102 may determine the second gain value as
described in FIG. 12 during a steady-state operation. Circuitry 102
may, in some examples, reduce the gain when the amplitude is higher
than a maximum threshold value and reduce the gain when the
amplitude is less than a minimum threshold value.
[0100] The following examples may illustrate one or more aspects of
the disclosure.
[0101] Example 1. A device for excitation of a resolver comprising
an excitation coil and one or more sensing coils, the device
comprising circuitry configured to: amplify a carrier signal using
a first gain value to generate an excitation signal for output to
the excitation coil of the resolver; determine whether the
excitation signal is outside of a threshold band of voltages; and
amplify the carrier signal using a second gain value, wherein the
second gain value is generated based on whether the excitation
signal is outside of the threshold band of voltages.
[0102] Example 2. The device of example 1, wherein, to determine
whether the excitation signal is outside of the threshold band of
voltages, the circuitry is configured to: determine whether a
voltage of the excitation signal exceeds a combination of a first
supply voltage and a first guard-band voltage; and determine
whether the voltage of the excitation signal is less than a second
supply voltage minus a second guard-band voltage.
[0103] Example 3. The device of any combination of examples 1-2,
wherein, to determine whether the excitation signal is outside of
the threshold band of voltages, the circuitry is configured to:
output the excitation signal to a first input of a first comparator
of the circuitry; output a first supply voltage to a second input
of the first comparator; apply, with a first guard-band element of
the circuitry, a first guard-band voltage that offsets a voltage at
the first input of the first comparator or a voltage at the second
input of the first comparator; output the excitation signal to a
first input of a second comparator of the circuitry; output a
second supply voltage to a second input of the second comparator;
and apply, with a second guard-band element of the circuitry, a
second guard-band voltage to offset a voltage at the first input of
the second comparator or a voltage at the second input of the
second comparator.
[0104] Example 4. The method of example 1, wherein the circuitry is
further configured to: output, to controller circuitry, a high rail
detection signal indicating that the excitation signal is in an
upper distortion zone in response to determining that the
excitation signal exceeds the threshold band of voltages; and
output, to the controller circuitry, a low rail detection signal
indicating that the excitation signal is in a lower distortion zone
in response to determining that the excitation signal is less than
the threshold band of voltages.
[0105] Example 5. The method of example 4, wherein the circuitry is
further configured to receive, from the controller circuitry, an
indication of the second gain value, wherein the controller
circuitry generates the second gain value based on the high rail
detection signal, the low rail detection signal, or both the high
rail detection signal and the low rail detection signal.
[0106] Example 6. The method of any combination of examples 1-5,
wherein the circuitry is further configured to determine the second
gain value based on whether the excitation signal is outside of a
threshold band of voltages.
[0107] Example 7. The method of example 6, wherein, to determine
the second gain value, the circuitry is configured to generate the
second gain value to be less than the first gain value when a
voltage of the excitation signal exceeds a combination of a first
supply voltage and a first threshold or when the voltage of the
excitation signal is less than a second supply voltage minus a
second threshold.
[0108] Example 8. The method of any combination of examples 6-7,
wherein, to determine the second gain value, the circuitry is
configured to generate, during a start-up operation of the
circuitry, the second gain value to be greater than the first gain
value when a voltage of the excitation signal does not exceed a
combination of a first supply voltage and a first threshold and
when the voltage of the excitation signal is less than a second
supply voltage minus a second threshold.
[0109] Example 9. The method of any combination of examples 6-8,
wherein, to determine the second gain value, the circuitry is
configured to generate, during a steady-state operation of the
circuitry, the second gain value to be greater than the first gain
value when a voltage of the excitation signal does not exceed a
combination of a first supply voltage and a first threshold, when
the voltage of the excitation signal is less than a second supply
voltage minus a second threshold, and when the excitation signal
comprises a voltage amplitude that is less than a signal integrity
threshold.
[0110] Example 10. The method of example 6, wherein, to determine
whether the excitation signal is outside of the threshold band of
voltages, the circuitry is configured to: determine a maximum
voltage of the excitation signal during a predetermined period of
time; and determine a minimum voltage of the excitation signal
during the predetermined period of time.
[0111] Example 11. The method of example 10, wherein the circuitry
is further configured to: output, to controller circuitry, an
indication of the maximum voltage and an indication of the minimum
voltage; and receive, from the controller circuitry, an indication
of the second gain value, wherein the controller circuitry
generates the second gain value based on the maximum voltage, the
minimum voltage, or both the maximum voltage and the minimum
voltage.
[0112] Example 12. The method of example 10, wherein the circuitry
is configured to determine the second gain value based on the
maximum voltage, the minimum voltage, or both the maximum voltage
and the minimum voltage.
[0113] Example 13. The method of any combination of examples 1-12,
wherein the one or more sensing coils comprises a sine sensing coil
and a cosine sensing coil and wherein the second gain value is
generated based further on a first amplitude of a sine sensing
signal at the sine sensing coil, a second amplitude of a cosine
sensing signal at the cosine sensing coil, or both the first
amplitude and the second amplitude.
[0114] Example 14. The method of any combination of examples 1-13,
wherein, to amplify the carrier signal using the first gain value,
the circuitry is configured to output the carrier signal into an
input of a programmable operation amplifier of the circuitry and
set a gain of the programmable gain operation amplifier to the
first gain value; and wherein, to amplify the carrier signal using
the second gain value, the circuitry is configured to output the
carrier signal into the input of the programmable gain operation
amplifier and set the gain of the programmable operation amplifier
to the second gain value.
[0115] Example 15. The method of example 14, wherein the circuitry
is formed in a single integrated circuit.
[0116] Example 16. A method for excitation of a resolver comprising
an excitation coil and one or more sensing coils, the method
comprising: amplifying, by circuitry, a carrier signal using a
first gain value to generate an excitation signal for output to the
excitation coil of the resolver; determining, by the circuitry,
whether the excitation signal is outside of a threshold band of
voltages; and amplifying, by the circuitry, the carrier signal
using a second gain value, wherein the second gain value is
determined based on whether the excitation signal is outside of the
threshold band of voltages.
[0117] Example 17. A system for excitation of a resolver comprising
an excitation coil and one or more sensing coils, the system
comprising: excitation circuitry configured to: amplify a carrier
signal using a first gain value to generate an excitation signal
for output to the excitation coil of the resolver; determine
whether the excitation signal is outside of a threshold band of
voltages; output an indication of whether the excitation signal is
outside of the threshold band of voltages; and controller circuitry
circuit configured to generate a second gain value in response to
the indication of whether the excitation signal is outside of the
threshold band of voltages, wherein the excitation circuitry is
configured to amplify the carrier signal using the second gain
value.
[0118] Example 18. The system of example 17, wherein the indication
of whether the excitation signal is outside of the threshold band
of voltages comprises a high rail detection signal indicating
whether the excitation signal is in an upper distortion zone and a
low rail detection signal indicating whether the excitation signal
is in a lower distortion zone; and wherein the controller circuitry
is configured to generate the second gain value based on the high
rail detection signal, the low rail detection signal, or both the
high rail detection signal and the low rail detection signal.
[0119] Example 19. The system of example 17, wherein the indication
of whether the excitation signal is outside of the threshold band
of voltages comprises an indication of a maximum voltage of the
excitation signal during a predetermined period of time and an
indication of a minimum voltage of the excitation signal during the
predetermined period of time; and wherein the controller circuitry
circuit is configured to generate the second gain based on the
maximum voltage, the minimum voltage, or both the maximum voltage
and the minimum voltage.
[0120] Example 20. The system of any combination of examples 17-19,
wherein, to amplify the carrier signal using the first gain value,
the excitation circuitry is configured to output the carrier signal
into an input of a programmable operation amplifier of the
excitation circuitry and set a gain of the programmable operation
amplifier to the first gain value; and wherein, to amplify the
carrier signal using the second gain value, the excitation
circuitry is configured to output the carrier signal into the input
of the programmable operation amplifier and set the gain of the
programmable operation amplifier to the second gain value.
[0121] Various aspects have been described in this disclosure.
These and other aspects are within the scope of the following
claims.
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